Sir – It has often been said that global warming is one of the biggest, if not the biggest challenge to face our generation at this point in history.

With this being the case, it is encouraging to see sustainability groups and transition towns pop up throughout Oxfordshire to help and encourage us to tackle this issue head on.

It was also positive that your paper covered the story of Sustainable Witney member Kate Griffin (Gazette, September 27), who lived plastic-free for a month, as it will hopefully inspire others to do the same.

I find it astonishing though that none of these groups seem to focus that much on our consumption of meat and dairy.

With a UN report a few years back quoting greenhouse gas emissions as 18 per cent for the livestock industry and a much less 13 per cent for all global travel, including cars, planes, ships, trains and buses. It seems that we should be focusing more on promoting a vegetarian or vegan diet to massively reduce our impact on the environment.

It seems that famous environmentalist and former US vice-president, Al Gore, has recently made the transition to a vegan diet. I wonder if this will encourage others?

This leaves me with a question. Can a true environmentalist also be a meat-eater, or would that by hypercritical?

Richard MacKenzie, Manor Road, Witney